The D-20 uses a single CMOS sensor the width of a
Super 35 film gate aperture. Effectively the D-20, when used with current 35 mm
PL mount motion picture lenses, yields the same
field of view and
depth of field as that of Super
35 mm film motion picture cameras.
The D-20 captures images in two main modes.
In Data mode the sensor uses 2880x2160 active pixels generating RAW
Bayer-data at
12 bit in a
4:3 aspect ratio. The RAW data then needs to be processed outboard to generate a full color image. A delivery aspect ratio for theatrical release, commonly
1.85:1, is achieved by cropping from the original image, similar to the cropping necessary when shooting 35 mm film. In Data mode the sensor size also allows for the use of
anamorphic lenses, producing the 2.35:1 widescreen aspect ratio from the full sensor height. Captured data is recorded to either flash or hard drives, notably the sTwo data recorder.
In HD Video mode the sensor uses 2880x1620 active pixels to generate an image with a
16:9 aspect ratio. This output is 1920x1080 pixels in either YUV 4:2:2
10 bit (via single link HD-SDI) or RGB 4:4:4
10 bit (via dual link HD-SDI). Typically, the D-20 is tethered to a Sony HDCamSR recorder. Other recording options exist, including the
Grass Valley flash mag which provides untethered recording of up to 15 minutes per "mag" in RGB 4:4:4.
The D-20 has a mechanical shutter, variable from 11.2° to 180° or an electronic shutter that simulates a 270° mechanical shutter at 24frame/s. The camera is capable of running at speeds from 1 to 48frame/s, though this shall be improved in the future. Numerous components of the camera were borrowed from Arri film camera models (most notably the
435ES), assuring compatibility with Arri film camera accessories and support equipment.
Though the D-20 system is capable of variable speeds from 1 to 60 frames per second in Data mode, these are currently limited to 23.976 frame/s, 24 frame/s, 25 frame/s, 29.97 frame/s & 30 frame/s in the video mode.
The sensitivity of the D-20 in video mode is regulated by the application of
LUTs (Look Up Tables) prior to output. With sensitivity settings ranging from ISO 100 to ISO 320 with linear responses, the D-20 also offers log curve options designed to mimic the response of film negative. Unlike some other digital cameras, the D-20 does not offer gain boost, instead relying on the advantages of adding gain in the post production process. The sensitivity of the camera in Data mode is regulated by applying
LUTs in the outboard processing of the image.
Distinctive Characteristics
Of the currently available high resolution digital motion picture cameras, the
Dalsa Origin, the SI 2K and the D-20 feature detachable optical viewfinders. Some advantages of an optical over purely electronic viewing systems include:
extremely high viewfinder resolution, with the option to zoom in on the image to check critical focus
availability of viewing area outside the image capture area, useful for predictive framing
ability to set camera framing without need of a power supply
Additionally, electronic viewing options can be added to the camera. Modifications to the camera filmbay have helped improve previous visual faults. Typically, the 6" Astro combination vector/waveform "onboard" monitor is used to both view and evaluate images for the camera.
Uniquely, the D-20 also accepts a traditional film style video assist system, sharing the image available through the optical viewfinder. This can be useful in Steadicam and remote crane applications where visibility outside the sensor capture area is preferable.
Like Arri film cameras, the D-20 is modularly constructed so that both the mechanical and electronic components are upgradable over time.
